This invention relates to an anti-theft alarm device for a vehicle, and more specifically relates to a device whose sound for confirmation at setting and sound at deactivation is softer than the sound of the alarm itself.
A conventional anti-theft alarm device for a vehicle has a motion detector which detects shaking of the vehicle. The motion detector is connected to a speaker in the vehicle via a control circiut which sounds the speaker. The control circuit has a receiver to receive an electric wave generated by a portable transmitter. The transmitter has a setting button and deactivation button for setting or deactivating the alarm. Thus, the device acts under wireless control. If the vehicle is shaken by a person, e.g., a thief, before deactivation, the motion detector detects movement and transmits the signal to the speaker. The speaker then emits a loud sound, drawing the attention of anyone nearby, and frightening the thief away.
In order to set the device when a driver leaves a vehicle, the driver pushes the setting button of the transmitter to "on". To deactivate the device on the driver's return, before opening the door to get in the vehicle, the driver pushes the deactivation button "on". Then, the door can be opened without the alarm sounding. When the driver pushes one of the buttons on the transmitter for the device to set or deactivate it, the speaker sounds for a moment to inform the driver that setting or deactivation is definitely completed.
A problem with the device described above is that when the device is set or deactivated, the sound of speaker is as loud as the alarm sound, it often startles people nearby, and the fact that the vehicle is protected by an anti-theft alarm is revealed.